పెరిస్కోప్

thumb|100px|left|Military handheld periscope optical 

design.
1 - Eyepiece 
2 - Diagonal prism 
3 - Handle
4 - 6 - Erecting lenses
5 - Periscope tube
7 - Field lens
8 - Lens
9 - Head diagonal prism
10 - Window

thumb|250px|right|Principle of the periscope.
 A - Periscope using two plane mirrors. 
 B - Periscope using two right–angled prisms.
1 - 2 - Plane mirrors.
3 - 4 - Right–angled prisms.
5 - 6 - Observer eye.
7 - 8 - Periscope tube.
H - Periscope optical height.
thumb|250px|right|Principle of the lens periscope.
 A - Periscope using a single lens (L2) to correct image.B - Periscope which uses two lenses (L2-L3) to correct image.1-3 - Periscope window.2-4 - Field stop or reticle.P - Right–angled prisms (or plane mirrors).L1 - Objective lens.L2 - for A - L2 - L3 - for B - Image erecting lens.L3 - L4 -for A - L4-L5- for B - Eyepiece.L0 - Field lens.y - Distant object.H - Periscope optical height.
నేత్ర స్థాయికి పైన గల అంశాలను వీక్షించేందుకు పెరిస్కోప్ సహకరిస్తుంది.